Add attachments-only filter to uploads

When uploading a file which is an e-mail, this option allows to skip
the mail body when the file is being processed.

modules/common/src/main/scala/docspell/common/ProcessItemArgs.scala

@@ -51,7 +51,8 @@ object ProcessItemArgs {
       skipDuplicate: Boolean,
       fileFilter: Option[Glob],
       tags: Option[List[String]],
-      reprocess: Boolean
+      reprocess: Boolean,
+      attachmentsOnly: Option[Boolean]
   )
 
   object ProcessMeta {

modules/common/src/main/scala/docspell/common/ScanMailboxArgs.scala

@@ -44,7 +44,9 @@ case class ScanMailboxArgs(
     // the language for extraction and analysis
     language: Option[Language],
     // apply additional filter to all mails or only imported
-    postHandleAll: Option[Boolean]
+    postHandleAll: Option[Boolean],
+    // Exclude the mail body when importing
+    attachmentsOnly: Option[Boolean]
 )
 
 object ScanMailboxArgs {